The present invention relates to an autoinjector.
Autoinjectors are well known in the prior art. The purpose of such devices is mainly to inject the contents of a syringe automatically into a patient's body. Various systems exist for making the penetration of the needle into the body of the patient and the injection of the fluid contained in the syringe automatic. Autoinjectors are relatively complex devices that must satisfy a certain number of constraint requirements in order to be reliable. The robustness of the device, its handling, and its ease of use for the user are also important elements. In addition, since most autoinjectors are for single use, the cost of manufacture and of assembly is also a factor that needs to be taken into account.
Numerous autoinjectors exist on the market, but they all present a certain number of drawbacks.
Thus, for autoinjectors that use the same spring both for initial pricking then for injection proper, the spring must be sufficiently strong to guarantee the injection stage in full. This is particularly true given that a relatively large force is generally required at the beginning of the injection stage, in order to start the movement of the piston of the syringe. As a result, the spring delivers its maximum power during pricking, which may make the pricking stage painful. Furthermore, with such a spring that is very powerful during pricking, there exists a significant risk of breaking the collar of the syringe, in particular when it is a glass syringe.
In addition, it may be desirable to have a visual and/or audible indication to inform the user that injection has terminated.
An object of the present invention is to provide an autoinjector that does not have the above-mentioned drawbacks, and that makes it possible to satisfy the various major requirements and constraints for safe and reliable use of the autoinjector.
Another object of the present invention is to provide an autoinjector that is reliable and safe in use, that makes it possible to guarantee that all of the fluid is dispensed to the desired location, that informs the user in reliable manner that injection has ended, and that is simple and inexpensive to manufacture and to assemble.